A conventional control device for an industrial sewing machine has been so constructed as to limit its application to the sewing machine in question as shown in FIG. 11. In the drawing, a sewing machine body 1 is provided with a motor 2 which is mounted thereon and to which a controller 4 for the sewing machine is connected by a motor controller 3. The controller 4 is connected to a synchronizer 5 in the body 1 and to system lines for controlling various solenoids. The controller 4 further includes a control panel 6 and a pedal 7 connected thereto.
As seen from FIG. 12, the controller 4 is designed so that a stitch number count control means 9 is connected to the output of a pattern stitch number setting means 8 and a needle position sensing or detecting means 10, respectively. The output of the stitch number count control means 9 is connected to a motor command control means 11 to which the output of a fore-pedaling amount detecting means 12 and a needle stop position setting means 13 are connected, respectively. The output of the motor command control means 11 is connected to a motor drive control means 14. The motor drive control means 14 is connected to the output of the needle position detecting means 10, a motor speed detecting means 15, and a motor angle detecting means 17, respectively. The output of the motor drive control means 14 is connected to a motor drive means 16, while the output of the motor drive means 16 is connected to the motor speed detecting means 15 and the motor angle detecting means 17. The output of an aft-pedalling sensing means 18 is connected to a thread cut mode setting means 19, the output of which is connected to the motor command control means 11 and a thread cut solenoid control means 20. The output of the thread cut solenoid control means 20 is connected to the thread cut mode setting means 19, a thread cut solenoid drive means 21, and a wiper solenoid control means 22 the output of which is connected to a wiper solenoid drive means 23. The output of a presser bar raising switch sensing means 24 is connected to a presser bar raising mode setting means 25 to which the output of the motor command control means 11 is also connected. The output of the presser bar raising mode setting means 25 is connected to a presser bar raising solenoid control means 26 the output of which is connected to a presser bar raising solenoid drive means 27. The output of the wiper solenoid control means 22 is also connected to the presser bar raising solenoid control means 26.
In a conventional control device for sewing machines as constructed above, a number of stitches initially set in control panel 6 is input to the stitch number count means 9 from the pattern stitch number setting means 8. When a fore-pedalling of the pedal 7 is sensed, the signal from the motor command control means 11 is high, and the motor drive control means 14 drives the motor 2 through motor drive means 16. The speed and angle of the motor are sensed by the respective means 15 and 17 and fed back to the motor control means 14 to control the motor 2. A number of stitches defined by the stitch number count control means 9 is subtracted by the signal from the needle position sensing means 10. After a stitch number count reaches 0, the signal from the motor command control means 11 is made low to stop the motor drive means 17 and to stop the needle in a position set by the needle stop position setting means 13.
When an aft-pedalling of the pedal 7 is sensed by the aft-pedalling sensing means 18, the thread solenoid control means 20 and the wiper solenoid control means 22 are activated by the thread cut mode setting means 19 to drive the thread cut solenoid drive means 21 and the wiper solenoid drive means 23. When sewing is completed, the output of the motor command control means 11 is low and a signal for raising a presser bar is input to the presser bar raising mode setting means 25, from the presser bar raising switch sensing means 24, so that the presser bar raising solenoid drive means 27 is driven by the output of the presser bar raising control means 26 to raise the presser bar to a predetermined position.
However, since such a conventional control device for sewing machines is arranged to set (fix) the timing of the thread cut solenoid drive means 21, the wiper solenoid drive means 23, and the presser bar raising solenoid drive means 27 and the like to accommodate the device within the mechanism of the sewing machine body 1, the content of memory means such as ROM and the like stored in the controller 3 must be changed when timings are set to differ from each other in the mechanism of the same sewing machine body 1. Particularly, if a mask ROM is used in the memory means, much time and expense is required for a change in the content thereof.
When a change in timing for each solenoid and the like is required for improvement of the sewing machine body 1 and stitch formation, difficulties are involved since the content of the memory means (ROM and the like) must be also changed.